1. Field of Invention
The present invention generally relates to a flexible transmission device, and more particularly relates to a flexible transmission device in which a cable or rope is used to pass through a narrow passage and connect two operating elements, so that a drag force can always be transmitted even when the relative distance between the two operating elements being changed.
2. Related Art
Using a flexible element, such as a cable or rope, to transmit a drag force is a well-known art. For example, a brake for a bicycle or a motorcycle generally uses a steel cable to transmit an operation force from a brake lever. Many foldable baby strollers, such as disclosed in U.S. Pat. Nos. 5,765,885; 5,769,447; 5,882,030; 5,622,377 and so on, use a similar flexible transmission device for releasing a latch mechanism for the folding-up purpose. The flexible device includes a steel cable for remotely pulling a latch mechanism or the like and releasing a foldable portion of the stroller.
In the aforesaid prior arts, the steel cable is loosely enclosed in a flexible tube, such as a plastic tube or a scrolled-wire tube. The flexible tube is fixed at both ends to the frame structure for guiding the steel cable moving therein responding to the operation. The two ends of the cable link respectively to an operation lever and an actuating member, such as a brake or latch. Since the elements on both ends of the cable are generally adjustable with relative positions, for instance, the brake lever of a bicycle will change its relative position or distance to the brake along with the height adjustment of the handle. Likewise, the control lever of a stroller will change its relative position or distance to the latch mechanism along with the folding operation of the frame. In the prior arts, the change of relative distance or position makes the flexible tube change its shape, such as the curve thereof. The different curve bending won""t influence the function, but it requires a certain length and space for the bending. Therefore, in the prior arts, the flexible cable and tube has to be long enough and loosely fixed outside the frame.
The aforesaid flexible cable and tube fixed outside a frame will not suitable for some foldable devices, especially when a compact structure is an important objective. For example, a foldable stroller is intended to be smaller when being folded. The length of the tube has to be shortened, which may constrain the operation of cable when being bent too much. Or, the bending causes inconvenience and bad looks of folding.
If we try to enclose the flexible cable and tube in the frame, such as the tube of the bicycle or stroller, then the limited space of the tube will constrain the bending of the cable, and make the solution unworkable.
It is therefore an object of the present invention to provide a flexible transmission device, which allows the change of length in the flexible elements.
Another object of the present invention is to provide a flexible transmission device, which can be enclosed in a limited space, such as a tube, and allows the change of length in the flexible elements.
The present invention uses flexible elements to link two operating members. When the relative distance between the two operating members changes, the flexible elements are still workable for transmitting a drag force.
To achieve the aforesaid objects, a flexible transmission device according to the present invention includes two flexible elements each having one end linking to an extendable mechanism, and each other end linking to a remote operating member respectively. The extendable mechanism includes a first tube and a second tube coaxially linking with each other so that the second tube is movable inside the first tube for changing the relative position or length of the two tubes that connect to the aforesaid two flexible elements respectively. In other words, when the two operating members linking at ends of the flexible elements change their relative positions, the extendable mechanism will change its length accordingly. The two flexible elements are defined as a first and a second flexible element. The first flexible element fixedly mounted along the axial direction of the extendable mechanism, with one end fixed to a first operating member, and the other end fixed to a slider movable along the second flexible element. The slider will be temporarily tilted to fix on the second flexible element when being pulled by the first flexible element so as to transmit the drag force. The second flexible element is fixed inside the extendable mechanism with one end fixed to the movable second tube, and the other end to the second operating member. The second flexible element can be moved in the axial direction of the extendable mechanism along with the axial length change of the extendable mechanism.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.